The researchers from the University of Rome base this assessment on observations in sixteen physically inactive women (age: 31±4; BMI: 27.5±2.1), who were randomly allocated to two groups that completed differently designed 12-week training programs.

All training sessions were performed under the supervision of an exercise specialist. Subjects completed a resistance circuit training consisting of 5 exercises on the following isotonic machines (Technogym, Gambettola, Italy):

For each exercise, 3 sets of 10 repetitions at 60% 1RM were performed requiring the subjects to provide the maximal contraction velocity, with a 30 seconds inter-set recovery, in an effort to induce the maximal power output for any specific movement 16 and to increase the metabolic stress. At the completion of the circuit, the same sequence was repeated for a second time.

Figure 1: Overview of the two workout combinations that were compared.

Immediately after the upper and lower body workouts, the subjects did 30-minute of steady-state low-intensity cardio at 50% of their individual pre-determined VO2max, either on a cycle ergometer (UpBdResist group) or on an arm-ergometer (LwBdResist group).

Figure 2: Significant differences were observed with DXA only for the upper limb fat and lean and the lower limb fat mass; figure shows relative changes in (kg) over the course of the 8-week study (di Palumbo 2017).

If we take a look only at the scientists' DXA-based regional body composition analyses in Figure 2, however, it doesn't really look as if there was a spot reduction effect. Rather than that, it appears as if lower body resistance training + upper body cardio simply burned more body fat than upper body RT + lower body cardio.

The skinfold data in Figure 3, on the other hand, suggests that the scientists' claim is not totally unwarranted. After all, the skinfolds declined more for those body parts that were trained in the respective workouts. Unfortunately, skinfolds measurements can be deceiving and are, compared to DXA data, depreciated as means of acquiring "detailed information about body composition" (Kitano 2017) - in that, the results of the di Palumbo study are in line with a 2007 study which found sign. reductions in skinfold thickness of the in subcutaneous fat adjecent to trained muscles. Unlike the authors of the the study at hand, Kostek, et al. (2007) have yet been able to check their skinfold measurements with MRI data and found "a generalized subcutaneous fat loss independent of whether they looked at the trained or the untrained arm in their 12-week resistance training itervention - for them, that was reason enough to conclude that "spot reduction does not occur as a result of resistance training" - it's possible that di Palumbo et al. would have come to the same conclusion if they'd had MRI scans of their subjects legs and arms, but who knows.

Figure 4: The scientists plotted the rel. changes in body fat without distinguishing between results from skinfold (arms vs. legs) and DXA (trunk vs. whole body) in one graph w/out explaining this difference in the caption (di Palumbo 2017).

So what's the verdict then? It would be premature to take the study at hand as the long-sought-for evidence for the ability to spot-reduce body fat by training those body parts, where you want to lose the most fat. Yes, the "treatment effect was greater in body districts performing resistance training and differed significantly between groups when matching according to body region" (di Palumbo 2017), in the absence of individual DXA data for the various parts of the upper body, it is yet not impossible that the skinfold measurements are misleading us; and I am absolutely not happy with the way the scientists plot the skinfold and DXA data in one and the same graph (see Figure 4) as this obscures the previously hinted at possible methodological issues.

The idea that you could mobilize the fat stores in the upper or lower body and then burn them in a subsequent cardio session is still intriguing; and the argument that cycling would burn more energy than the arm-ergometer, which would invalidate the results is questionable - and that despite the fact that the scientists themselves mention it in the paragraph about limitations of their study. After all, one would expect to see a greater total body fat loss in the upper body RT + lower body cardio group, which is something of which you already know that it wasn't observed in the study at hand (the same net effect should be observed if a difference in fat oxidation between cycling vs. arm cranking messed with the results). Against that background and in view of the fact that previous studies have confirmed at least part of the authors' theory, i.e. an increased rate of lipolysis in trained body parts (Stallknecht 2007), I would be positively optimistic that a minor effect may indeed exist. And since we need studies to confirm its existence in other study populations, like young men, for example, I am pretty sure there's going to be more research that may answer the question whether the juxtaposed reductions in leg and arm fat, the scientists measured in the study at hand are methodological artifacts or a real instance of real spot-reduction | Comment!

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